I use a propane powered welder/generator when I work or weld in food plants. I like them, here are my reasons-
1. If you spill gasoline you have a mess and an odor that lingers, If you leak propane the smell disperses pretty quickly.
2. Your oil and spark plug will last longer with propane.
3. Since propane is under pressure, you shouldnt have much trouble starting the engine in different weather or altitude changes.
4. propane gives off Carbon Dioxide and gasoline gives off Carbon Monoxide.
5.Propane engine isnt as efficient as Gasoline, not much of a difference but over time it will be a big difference.
There are a few other differences, but dont get me wrong, A Gasoline powered Honda generator will last a long time with regular maintenance.
Good luck, ask Google , It knows a lot more than I do.